New £350,000 bat bridges installed on the recently-dualled stretch of A11 are not working, a study has revealed.

Designed to help bats cross roads, the bridges feature wire mesh strung high over the carriageway between two poles.

The wire mesh is intended to replace hedgerows and trees that have been removed, giving the bat a reference point for sonar, so that they can avoid the road when flying.

The bridges have been heavily criticised over concerns they are ineffective and a waste of money.

Six of the bridges were installed on the new stretch of A11 between Thetford and Barton Mills, after six bat species were detected in the surrounding area before the project started in 2013.

But a study from Anna Berthinussen and John Altringham at the University of Leeds, produced for Defra, reveals that the bridges are not helping bats avoid the road.

The study focused on three bridges and an overbridge on the Elveden bypass section of the road.

It found that most bats ‘used’ the bridges at unsafe heights, with more than 80pc flying below five metres above the road.

This was in stark contrast to the target of at least 90pc of bats using the bridges as intended, in order for it to be considered effective.

It says: “We can conclude that neither of the installed bat wire bridges is effective in guiding bats safely over the road.”

A spokesman for the Highways Agency, which ran the A11 dualling project, said it took its “environmental responsibilities seriously”.

“Bats are an important part of our native wildlife and as a protected species we are legally obliged to protect them. We plan bespoke crossing structures, such as bat wire bridges, when all other options have been discounted.

“The measures on the A11 were modified from previous designs on our network to improve their potential for use by bats and were part of a larger package, including a landscaping programme and artificial bat roosts, intended to support local bat populations,” she said.

Dr Stuart Newson, project manager for Norfolk Bat Survey and senior research ecologist for the British Trust for Ornithology, said bat bridges were being installed without sufficient evidence.

“There haven’t been enough studies done to show if the bridges work in particular situations, but the current evidence we do have is that they aren’t.

“Decisions on bats need to be guided by more data. We should be investing in studies which will save us money in the long run.

“Overall though, I’d rather see bats being considered than not when these projects take place,” he said.

What do you think of the use of bat bridges? Are they a waste of money? Email andrew.fitchett@archant.co.uk

I love bats, but am baffled as to how these were deemed necessary or work. Dear Archant Journo, please once again stop with canned spokesperson responses and name and shame who actually signed off on this wastage? We need to start exposing the people responsible for these. Then this kind of thing might stop if they know they might get called out for it.

We have many power lines at home and those in the actual or potential flight paths of aircraft, of which there are many, have such balls to make the power lines obvious to aircraft pilots. Such is also the case across most of Western Europe. I just confirmed on a well known search engine that this is the reason for their placement. We even have them on many of the tower links on ski lifts when the towers are inter-coupled by a reinforcing catenary and for the same reason.

Bats want to hunt by light and are attracted by the cars, unless off course, one would use these existing pylons to attach some lights to them at a slightly higher than traffic height, i.e above 4.4 m. The worst would be to take these down and leave the bats to hunt using the car lights. They are quick to react, but there would be fatalities, so the lights above these poles, shining slightly upwards would let them hunt in safety. If this bridge failed, then my idea should be followed up, its easy to install and they would not cost much, these lights could partially be powered by solar panelswind generators, but there are also service channels one could tap into.

Again Koenig thinks he is an expert on everything but proves he knows nothing. The balls on power cables are called "flight diverters" and are designed to make powerlines visible to large birds who may otherwise not see them and become injured.

The ridiculous things are totally unnecessary and serve no useful purpose whatsoever. As for fitting 'warning balls', if the bat bridges were not in place there would be no wire crossing the road for the bats to be warned of, secondly the balls when fitted to cable spans are intended to make such wires visible to low flying aircraft including helicopters.

Bats are a "brick in the wall" of the environment which gives us humans life itself. When we've removed enough bricks, the wall will fall down. Money won't be so important then..............I wonder if incorporating more mesh screen attached to the wire, would give more surface area to reflect the bats' sonar, and so guide them. I notice that power lines where swans fly, have bright red globes attached. Presumably that is effective, a good example of how these problems can be dealt with, and they must be dealt with.

Bats are a "brick in the wall" of the environment which gives us humans life itself. When we've removed enough bricks, the wall will fall down. Money won't be so important then..............I wonder if incorporating a mesh screen attached to the wire, would give more surface area to reflect the bats' sonar, and so guide them. I notice that power lines where swans fly, have bright red globes attached. Presumably that is effective, a good example of how these problems can be dealt with, and they must be dealt with.

£350000?! I had no idea wood and wire was so expensive. Rumours has it that the Highways Agency are now considering alternative solutions including a bat 'flying school' and a more traditional 'Stop. Look. Listen' approach.

Seems to me that the government is generating far too much in tax dollars if it can afford to waste money in this way. How about a reduction in VAT back to earlier levels to tax takings to promote sensible spending. Is that just batty ?

What a waste of money - that could have gone towards providing a decent solution to the Five-ways Roundabout problem. As the bat bridges don't work as expected, perhaps the powers that be could claim breach of contract or mis-selling and recover the monies? Yet again the tax payer is being short-changed.

Shock horror gasp - it's all been a waste of money. Could not see this coming! Some of the people who call themselves environmentalists may be highly qualified but that does not mean they are very bright! As for 'investing' in further studies, the last thing we need to do is waste more money. What on earth made anyone think that bats would try to use these structures?

All the miles I have driven over a lot of years I can't say I have ever knowingly struck a bat found a bat stuck in the front of my car nor noticed one in my headlights. It is a laudable thing to try to prevent bats being killed, but the length of the A11 where the trees were touching at the top...really? Must have been a very short distance. I thought bats had rather sensitive hearing although I know they can block sound-surely the noise and smell from a road is enough to deter them. Another big money waste has been the planting of largish specimen Scots pine and then failing to water them-daft, done for appearances sake when small specimens would have grown better, Now they are almost all dead. If they want something to do beside the A11 they need to get more deer posts up-much as I like seeing red deer and roe deer I prefer not to see them right beside the road at night.

Some years ago bats had got under my flat roof garage, and were clearly breeding there. The smell was awful, they are horrible creatures. I know they are "protected" but I managed to smoke them out, and counted at least 250 of them making a move to a better place. They had left droppings everywhere. For those who want them protected, invite them to your property.
It once again proves there is no limit to what these people are given to spend on the stupid ideas.
Said to say it seems that all natures animals are far, far more important than human ones.
The person or persons who authorise this type of spending should be sacked, and find a proper job in the real world.

Another £350,000 of hard earned tax-payers money down the U-bend. Another hospital short of nurses and less funds to care for the elderly. Will the people who spent the money be held to account and invited to repay it? As ever, completely batty.............................

Well obviously they are if they are not working. How about a quick study as to how many are fond dead. If not that many then why bother. The £350,000 could of then been spent on improving the 5-ways roundabout, which was always going to be a problem once the road was completed. It beggars belief that nobody had the foresight to see that one coming...but then I can only presume people plan from a nice warm office, instead of getting out there.